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1,610 results for “ratio”
Dietary fat supplements influence weight gain and egg production but not offspring sex ratios in Japanese quail
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Data from: The sources of variation for individual prey-to-predator size ratios
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Data from: Climate warming and sea turtle sex ratios across the globe
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Data from: Beyond pollen:ovule ratios: Evolutionary consequences of pollinator dependence and pollination efficiency for pollen and ovule production in angiosperms
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Multiple paternity is related to adult sex ratio and sex determination system in reptiles
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Environmental variation in sex ratios and sexual dimorphism in three wind-pollinated dioecious plant species
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Data for: Mechanisms that can cause population decline under heavily skewed male-biased adult sex ratios
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Acclimation of phytoplankton Fe:C ratios dampens the biogeochemical response to varying atmospheric deposition of soluble iron
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Spatial Access Ratio, Albuquerque, NM
GIS-based spatial access measures have been used extensively to monitor social equity and to help develop policy and planning for provision of public services. However, uncertainties in the road datasets used to calculate measures of spatial access remain largely underreported. These uncertainties might result in biases within decision-making that strives for social equity based on seemingly egalitarian accessibility metrics. To better understand and address these uncertainties, we evaluated variations in travel impedance resulting from street layer uncertainty (e.g. proprietary, free, and volunteer-information-based streets) and its propagation in a multi-modal enhanced 2-step floating catchment area (MM-E2SFCA) model of spatial accessibility for car and bus transportation, using datasets in the metropolitan area of Albuquerque, NM, USA. We proposed and demonstrated a novel approach as a solution – the spatial access ratio (SPAR). Results indicate that travel impedance disagreement among different street sources propagate through the modeling process to effect Spatial Access Index (SPAI) estimates. Less urbanized regions were found to experience higher street-source variations when compared with the core-metropolitan area. SPAR reduced uncertainties introduced by the choice of model parameter or street datasets, providing a suitable alternative to SPAI for analyses that do not require an absolute measure of supply to demand ratio. Careful selection of street source data and consideration of the potential for bias, particularly for less urbanized areas and areas reliant on public transportation, is warranted when leveraging SPAI to inform policy.
Estimates of surface layer net community production based on underway Lagrangian measurements of the dissolved O2/Ar ratio using Equilibrator Inlet Mass Spectrometry (EIMS), based on both steady-state and non-steady-state assumptions of the mixed-layer biological oxygen budget. Also included are estimates of the potential contribution of vertical fluxes: advection, eddy diffusion, and entrainment.
The ratio of dissolved oxygen to argon in surface seawater is frequently employed to estimate rates of net community production (NCP) in the oceanic mixed layer. The in situ O2/Ar-based method accounts for many physical factors that influence oxygen concentrations in the surface ocean, permitting isolation of the biological oxygen signal produced by the balance of photosynthesis and respiration. However, this technique traditionally relies upon several assumptions when calculating the mixed layer O2/Ar budget, most notably the absence of vertical fluxes of O2/Ar and the existence of a steady-state balance between net productivity and the air-sea gas exchange of biological oxygen. Employing a Lagrangian study design and leveraging data outputs from a regional physical oceanographic model, we conducted in situ measurements of O2/Ar in the California Current Ecosystem in spring 2016 and summer 2017 to evaluate these assumptions within a ‘worst-case’ field environment. Quantifying the magnitude of vertical fluxes and comparing NCP estimates obtained using steady-state versus non-steady-state assumptions, we find the importance of the non-steady-state term to be considerable, also observing significant potential effects from vertical flux terms, particularly advection. Additionally, we observe strong diel variability in O2/Ar and calculated NCP rates at multiple stations. Our results reemphasize the importance of accounting for vertical fluxes when interpreting O2/Ar-derived NCP data as well as the potentially large effect of non-steady-state conditions, including diel cycles in surface O2/Ar that can bias interpretation of NCP data based on local productivity and the time of day at which measurements were made.
McMurdo Dry Valleys Microbial mat biomass, isotopes, and nutrient ratios sampled over a longitudinal gradient of two McMurdo Dry Valley streams
We performed a field survey to assess changes in biomass, nutrient ratios, and isotopic signatures of three different microbial mat types in two glacial meltwater streams in the McMurdo Dry Valleys, Antarctica. Samples were taken in January 2013 from pre-existing transects over Von Guerard Stream and the Relict Channel, and stretched from near the Von Guerard Glacier terminus to the stream outlets at Lake Fryxell. In addition to the three microbial mat types, which included Nostoc (black), Chlorophyte (green), and Oscillatorean (orange) mats, particulate organic matter (POM) was collected from Von Guerard Stream in January 2008 over a full diel cycle in order to determine the origin of material in transport by comparing its elemental and isotopic characteristics with stream mats.
Single-protein simulations with a varying lipid-to-protein ratio
<p>Coarse-grained (Martini) simulations of a single protein in membranes with a varying number of DPPC lipids. There are 400, 200, 100, 75, or 50 lipids per leaflet. The simulation parameters follow DOI:10.5281/zenodo.846428, and the required topologies can also be obtained from that upload. Details on the simulations are given in (ADD CITATION LATER). </p>
EMAC-MESSy source segregated CH4 mixing ratios simulated along CARIBIC flight tracks
<p>The *.zip archives contain netCDF data files with EMAC-model simulated CH4 mixing ratios (nmol/mol) along CARIBIC-flight tracks during the years 1997 through 2016 in the upper troposphere and lowermost stratosphere.</p> <p> </p> <p>CARIBIC2org.zip:</p> <p>Every .nc file contains time, lon, lat, and track pressure of the flight simulation and the vertical column of mixing ratios in hybride coordinates total CH4 and eleven source segregated (tagged) contributions. For a best fit of the observations the .nc files have to be multiplied with the scale factors in column 3.</p> <p> </p> <p>CARIBIC_tag_emi_org*CARIBIC2.nc:</p> <p>Tracer: variable name:</p> <p>CH4 total tracer_gp_CH4_fx</p> <p> </p> <p>CH4 tagged: variable name: scale:</p> <p>animals tracer_gp_CH4_fx_e01_a01 0.87</p> <p>bogs tracer_gp_CH4_fx_e02_a01 1.04</p> <p>coal tracer_gp_CH4_fx_e03_a01 0.87</p> <p>gas tracer_gp_CH4_fx_e04_a01 0.89</p> <p>landfills tracer_gp_CH4_fx_e05_a01 0.95</p> <p>oil tracer_gp_CH4_fx_e06_a01 0.91</p> <p>rice tracer_gp_CH4_fx_e07_a01 1.04</p> <p>swamps tracer_gp_CH4_fx_e08_a01 1.13</p> <p>termits tracer_gp_CH4_fx_e09_a01 1.13</p> <p>biomass burn tracer_gp_CH4_fx_e10_a01 1.13</p> <p>biofuel tracer_gp_CH4_fx_e11_a01 1.13</p> <p> </p> <p>CARIBICric.zip, CARIBICsha.zip: CARIBICtro.zip:</p> <p>In these arcives every .nc file contains time, lon, lat, and track pressure of the flight simulation and the simulated mixing ratios along the flight tracks for the post 2006 CH4 increments to be added to the above totals. The increments have to be scaled with the factors in colums 3 for an optimal fit of the observations.</p> <p>CARIBICric.zip: CARIBIC_tag_emi_ric*.nc</p> <p>Tracer: variable name: scale:</p> <p>CH4 rice tracer_gp_CH4_fx 0.48</p> <p> </p> <p>CARIBICsha.zip: CARIBIC_tag_emi_sha*.nc</p> <p>Tracer: variable name: scale:</p> <p>CH4 shale gas tracer_gp_CH4_fx 0.48</p> <p> </p> <p>CARIBICtro.zip: CARIBIC_tag_emi_tro*.nc</p> <p>Tracer: variable name: scale:</p> <p>CH4 tropics tracer_gp_CH4_fx 0.04</p> <p> </p> <p>The mixing ratios are based on emission amounts of 20.5 Tg/CH4/y for each, rice-, shale gas fracking-, and tropical wetlands. The best fit of the observations is a combination of them multiplied with the scale factors in column 3.</p> <p> </p> <p> </p> <p>The corresponding CH4 total mixing ratios (together with other species) are available on demand via <a href="http://www.caribic-atmospheric.com/">http://www.caribic-atmospheric.com</a> "Data access".</p> <p> </p> <p>References:</p> <p>This study:</p> <p>Zimmermann, P. H., Brenninkmeijer, C. A. M., Pozzer, A., Jöckel, P., Winterstein, F., Zahn, A., Houweling, S., and Lelieveld, J.: Model simulations of atmospheric methane (1997–2016) and their evaluation using NOAA and AGAGE surface and IAGOS-CARIBIC aircraft observations, Atmos. Chem. Phys., 20, 1–23, <a href="https://doi.org/10.5194/acp-20-1-2020">https://doi.org/10.5194/acp-20-1-2020</a> ,2020</p> <p>The CARIBIC project:</p> <p>Brenninkmeijer, C. A. M., Crutzen, P., Boumard, F., Dauer, T., Dix, B., Ebinghaus, R., Filippi, D., Fischer, H., Franke, H., Fries, U., Heintzenberg, J., Helleis, F., Hermann, M., Kock, H. H., Koeppel, C., Lelieveld, J., Leuenberger, M., Martinsson, B. G., Miemczyk, S., Moret, H. P., Nguyen, H. N., Nyfeler, P., Oram, D., O'Sullivan, D., Penkett, S., Platt, U., Pupek, M., Ramonet, M., Randa, B., Reichelt, M., Rhee, T. S., Rohwer, J., Rosenfeld, K., Scharffe, D., Schlager, H., Schumann, U., Slemr, F., Sprung, D., Stock, P., Thaler, R., Valentino, F., van Velthoven, P., Waibel, A., Wandel, A., Waschitschek, K., Wiedensohler, A., Xueref-Remy, I., Zahn, A., Zech, U., and Ziereis, H.: Civil Aircraft for the regular investigation of the atmosphere based on an instrumented container: The new CARIBIC system, Atmos. Chem. Phys., 7, 4953-4976, doi:10.5194/acp-7-4953-2007, 2007.</p> <p>EMAC atmospheric chemistry model:</p> <p>Jöckel, P., Kerkweg, A., Pozzer, A., Sander, R., Tost, H., Riede, H., Baumgaertner, A., Gromov, S., and Kern, B.: Development cycle 2 of the Modular Earth Submodel System (MESSy2), Geosci. Model Dev., 3, 717-752, doi:10.5194/gmd-3-717-2010, 2010.</p> <p> </p> <p> </p> <p> </p>
Data from: Nitrogen fertilizer decreases survival and reproduction of female locusts by increasing plant protein to carbohydrate ratio
<p>1. Nitrogen limitation theory predicts that terrestrial plants should benefit from nitrogen inputs and that herbivores should benefit from subsequent higher plant protein contents. While this pattern has generally been supported, some herbivorous insects have shown preference and higher performance on low protein (p), high carbohydrate (c) diets as juveniles.</p> <p>2. However, little is known about the effects on reproduction in adults. Using nitrogen fertilizer, we demonstrate that high plant p:c has negative effects on Senegalese locust (Orthoptera: Oedaeleus senegalensis) reproduction and survival in an agroecological setting.</p> <p>3. For this, we measured p:c in millet plants (Pennisetum glaucum) that received two levels of fertilizer (high and moderate) and a control, then we caged locusts on these plants for two weeks. In the laboratory, we gave locusts the choice between untreated millet leaves and leaves that received one of the two fertilization treatment.</p> <p>4. We found that fertilization increased p:c ratio in a concentration dependent fashion. We counted the number of locusts alive over the course of two weeks and showed that fewer females survived on fertilized plants than on control plants. Females that ate plants from the high fertilization treatment laid lighter eggs. Finally, we showed that female locusts prefer unfertilized plants to plants with a high p:c.</p> <p>5. We hypothesize that this pattern will apply broadly to species that have extensive carbohydrate needs, such as long-distance migrators. Because many ecological studies focus primarily on nitrogen or protein, and fail to consider carbohydrates, this study has important implications for how ecologists consider nutrient limitation of primary consumers in ecosystems globally. </p>
Data from: Total Aβ42/Aβ40 ratio in plasma predict amyloid-PET status, independent of clinical AD diagnosis
Background: Research has focussed upon the identification of a blood-based biomarker to inform clinicians on the likelihood of Alzheimer's disease pathology prior to ordering the CSF and PET testing. Objective: To explore if the plasma total Aβ42/Aβ40 ratio is a reliable predictor of the amyloid-PET status we have explored the association between these two variables in a subset of the Australian Imaging, Biomarkers and Lifestyle (AIBL) study of ageing cohort. Methodology: Taking plasma samples at three separate time points, we assessed the total Aβ42/Aβ40 ratio in plasma (TP42/40) with regard to neocortical amyloid beta (Aβ) burden via PET SUVR, and investigated both association with Aβ-PET status and correlation (and agreement) with SUVR. Results: The TP42/40 plasma ratio was associated with PET status at all time points (p<0.013). Correlations with SUVR were similar across each time point, with Spearman's Rho reaching -0.64 (p<0.0001). Area under the curve (AUC) values were highly reproducible over time points, with values ranging from 0.880 at 36 months to 0.913 at 54 months. Assessing the healthy control (HC) group only, the same relationships were found. Conclusions: The current study demonstrates reproducibility of the plasma assay to discriminate between amyloid-PET positive and negative over three time points, which can help to substantially reducing the screening rate of failure (SRF) for clinical trials targeting pre-clinical or prodromal disease. Classification of evidence: This study provides Class II evidence that plasma total AB42/AB40 ratio is associated with neocortical amyloid burden as measured by PET SUVR.
Data from: Macroevolution of desiccation-related morphology in plethodontid salamanders as inferred from a novel surface area to volume ratio estimation approach
Evolutionary biologists have long been interested in the macroevolutionary consequences of various selection pressures, yet physiological responses to selection across deep time are not well understood. In this paper, we investigate how a physiologically-relevant morphological trait, surface area to volume ratio (SA:V) of lungless salamanders, has evolved across broad regional and climatic variation. SA:V directly impacts an organisms' ability to retain water, leading to the expectation that smaller SA:Vs would be advantageous in arid, water-limited environments. To explore the macroevolutionary patterns of SA:V, we first develop an accurate method for estimating SA:V from linear measurements. Next, we investigate the macroevolutionary patterns of SA:V across 257 salamander species, revealing that higher SA:Vs phylogenetically correlate with warmer, wetter climates. We also observe higher SA:V disparity and rate of evolution in tropical species, mirrored by higher climatic disparity in available and occupied tropical habitats. Taken together, these results suggest that the tropics have provided a wider range of warmer, wetter climates for salamanders to exploit, thereby relaxing desiccation pressures on SA:V. Overall, this paper provides an accurate, efficient method for quantifying salamander SA:V, allowing us to demonstrate the power of physiological selection pressures in influencing the macroevolution of morphology.
Data from: Biological stoichiometry of oleaginous microalgal lipid synthesis: The role of N:P supply ratios and growth rate on microalgal elemental and biochemical composition
<p>Biological Stoichiometry is an ecological framework connecting the balance of elements to the functioning of organisms. Here, we applied this framework to study the relationships between carbon:nitrogen:phosphorus (C:N:P) ratios and synthesis of industrial high value biochemicals in the highly oleaginous alga <em>Tetradesmus bernardii.</em> We expected an increase in protein content with increasing cellular N content and decreasing C:N stoichiometry, and an increase in lipid content with increasing C:N and C:P stoichiometry. We tested these hypotheses by exposing <em>T. bernardii</em> to N and P limitation at a range of N:P supply ratios in chemostats set at low and high dilution rates. Following expectations, the cellular protein content increased with the N content, and decreased with cellular C:N ratios across all treatments. Carbohydrates and lipids largely followed the relative availability of C and increased under both N and P limitation, with higher C:N and C:P ratios. Specifically, lipid content increased by 100–125% upon N and P limitation, with a shift towards more neutral lipids at the cost of glycolipids and phospholipids. Generally, we observed a re-allocation of cellular C from protein to carbohydrates upon modest N limitation, and towards lipids under P and severe N limitation. Our results demonstrate stoichiometrically predictable patterns of industrially valuable compounds in an oleaginous microalga.</p>
Offspring sex-ratios are stable across the life-course in Drosophila simulans
Within populations, adult sex ratios influence population growth and extinction risk, mating behaviors and parental care. Additionally, sex ratio adjustment can have pronounced effects on individual fitness. Accordingly, it is important that we understand how often, and why, offspring sex ratios deviate from parity. In Drosophila melanogaster, females appear to improve their fitness by producing fewer sons when paired with older males. However, facultative sex ratio adjustment in D. melanogaster is controversial, and our understanding of how sex ratio skew affects fitness is hampered by pronounced sexual conflict in this species. Additionally, it is unclear if maternal age or quality interact with paternal age to influence offspring sex ratios. Here, we test whether offspring sex ratios vary as a function of maternal quality, and maternal and paternal age in Drosophila simulans, a sister species of D. melanogaster that lacks overt sexual conflict. We find that offspring sex ratios are slightly male biased overall, but constant across the female life-course, and independent of female quality, or paternal age. To really understand if, how and when females skew offspring sex ratios, we need studies linking offspring sex ratios to male and female phenotypes that are predicted to shift optimal investment in sons and daughters.
Causes and consequences of an unusually male-biased adult sex ratio in an unmanaged feral horse population
<p>1. The adult sex ratio (ASR) is important within ecology due to its predicted effects on behaviour, demography, and evolution, but research examining the causes and consequences of ASR bias have lagged behind studies of sex ratios at earlier life stages. Although ungulate ASR is relatively well-studied, exceptions to the usual female-biased ASR challenge our understanding of the underlying drivers of biased ASR, and provide an opportunity to better understand its consequences.</p> <p>2. Some feral ungulate populations, including multiple horse populations, exhibit unusually male-biased ASR. For example, research suggests that the feral horse (Equus ferus caballus) population on Sable Island, Nova Scotia, Canada, may exhibit a male-biased ASR. Such exceptions to the rule provide a valuable opportunity to reveal the contributions of environmental context and trait differences to ASR bias.</p> <p>3. We aimed to test for bias in Sable Island horse ASR, identify the demographic drivers of bias, and explore its demographic and social consequences. To do this, we used life-history, movement, and group membership information for hundreds of horses followed through a long-term individual-based study between 2007 and 2018.</p> <p>4. Sable Island horse ASR is male-biased, and this skew has increased over time, reaching 62% male in 2018. Our life table response experiment suggested that ASR skew was driven predominantly by male-biased adult survival. Further analyses pointed to sex-biased survival being driven by reduced female survival post-reproduction. Male-biased ASR was associated with reduced harem sizes, an increase in the number of social groups on the island, and reduced reproduction in young females.</p> <p>5. Our results support the idea that male-biased ASR in feral ungulate populations may be caused by a combination of high population density and high reproductive output. We suggest that female-biased mortality may be caused by females continuing to reproduce at high density, and thus being more susceptible to resource shortages. Thus, our results highlight the strong context-dependence of ASR. Furthermore, our work indicates the potential for ASR to substantially alter a population's social organisation. Such changes in social structure could have knock-on consequences for demography by altering the formation/stability of social relationships, or competition for matings.</p>
Mixing ratios and FRFs of ODSs observed in air samples from research aircraft campaigns in 2016 and 2017
<p>This data set consists of mixing ratios and fractional release factors of ozone-depleting substances measured in air samples collected during research aircraft campaigns in 2016 and 2017 which were both sampling air masses related to the upper part of the Asian Summer Monsoon and above. These activities were part of the EU Stratoclim-603557 project and a corresponding manuscript has been submitted to the journal JGR Atmospheres. This version also includes the supplement of that manuscript.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.